Effect of phenobarbital pretreatment on the metabolism and antitumor activity of hexamethylmelamine

The effect of phenobarbital (PB) pretreatment on the N-demethylation and antitumor activity of hexamethylmelamine (HMM) was investigated in mice. In mice pretreated with PB, the levels of HMM in plasma, liver, and M5076 tumor were much lower than in mice treated with HMM alone. Plasma area under the curve (AUC) values were 15 +/- 4 versus 37 +/- 28 micrograms/ml X min, liver AUC values were 43 +/- 13 versus 246 +/- 5 micrograms/g X min, and tumor AUC values were 37 +/- 14 versus 109 +/- 24 micrograms/g X min. All of the N-demethylated metabolites except N2N4 dimethylmelamine in plasma, liver, and tumor also reached much lower levels in mice pretreated with PB. The antitumor activity of HMM was significantly antagonized by PB treatment in both M5076 reticular cell sarcoma and PC6 plasmocytoma of the mouse.

Pentamethylmelamine: review of an aqueous analog of hexamethylmelamine

The s-triazine derivatives have shown preclinical antitumor activity against several histologic types. The most widely used compound of this class in the clinic, hexamethylmelamine, has been largely restricted to oral use because of its low solubility and lack of stability in solutions suitable for parenteral administration. New analogs were sought which were soluble and stable and retained antitumor activity. Pentamethylmelamine (PMM), the monodemethylated derivative, showed these promising characteristics. Preclinical toxicology studies of PMM in mice, dogs, and monkeys showed toxic manifestations that involved the hematopoietic, lymphatic, renal, male reproductive, gastrointestinal, and nervous systems; these changes were both infusion-rate- and dose-dependent. Clinical phase I trials of PMM were performed using a variety of infusion durations and frequency schedules. The dose-limiting toxic effect common to all of these trials was protracted nausea and vomiting. In addition, some studies reported dose-limiting central nervous system manifestations in the form of agitation, drowsiness, somnolence, and even coma. Mild to moderate hematologic changes were noted. Because of the severity and frequency of the gastrointestinal and central nervous system toxic effects observed in the completed trials, no new clinical trials of PMM sponsored by the National Cancer Institute are planned. However, the interest in finding a clinically useful parenteral triazine continues.

Hexamethylmelamine, methotrexate, 5-fluorouracil as second line chemotherapy after platinum for epithelial ovarian malignancies

Thirty-three patients were treated with HexAF after previous treatment with cyclophosphamide (C), Adriamycin (A), and cisplatin (P). The patients had either progressed on CAP, had persistent disease after CAP, or recurred after a negative second look. Treatment schedule was hexamethylmelamine (Hex) 150 mg po qd days 1-14, methotrexate (A) 40 mg/m2 IV days 1 and 8, and 5-fluorouracil (F) 600 mg/m2 IV days 1 and 8. Courses were repeated every 4 weeks. Thirty-one of 33 patients were evaluable for response. Three of 31 patients had partial responses, 7 of 31 had stable disease, and 21 of 31 progressed. Median survival of the responders (n = 3) was 23 months and the nonresponders (n = 28) was 6 months (p = 0.027). Patients with less than 1 cm disease (n = 12) had a median survival of 20 months, and those with greater than 1 cm (n = 21) had a median survival of 6 months (p = 0.004). Toxicity was mild. Even with a statistically significant survival advantage for HexAF responders, we consider a response rate of less than 10% unacceptable.

Comparison of cyclophosphamide plus cisplatin versus hexamethylmelamine, cyclophosphamide, doxorubicin, and cisplatin in combination as initial chemotherapy for stage III and IV ovarian carcinomas

Among 187 women with stage III and IV ovarian carcinoma who participated in this comparative clinical trial, 181 were eligible for analysis. Of these patients, 89 received monthly treatment with CP [cyclophosphamide (1 g/m2) plus cisplatin (60 mg/m2)] and 92 received monthly treatment with HCAP [hexamethylmelamine (150 mg/m2/day X 7), cyclophosphamide (400 mg/m2), doxorubicin (30 mg/m2), and cisplatin (60 mg/m2)]. All treatments were administered iv on Day 1 of each monthly treatment cycle, except for hexamethylmelamine, which was administered orally on Days 2-8. With a median follow-up time of 30 months, survival curves for the two treatment groups were almost identical, as were their times to progression [estimated median survival, 24.6 months (Kaplan-Meier)]. Patient characteristics which significantly influenced survival were age, degree of histologic differentiation, extent of residual disease, stage of disease, and histologic type. Results of posttreatment laparotomies have been equal for the two treatment groups. Toxic effects of the two regimens have been similar, except for more frequent, more severe, and earlier neurotoxicity among patients treated with HCAP. Of the two regimens, CP has the better therapeutic index.

Mullerian inhibiting substance reduction of colony growth of human gynecologic cancers in a stem cell assay

Mullerian Inhibiting Substance (MIS), a fetal testicular product that causes regression of the Mullerian duct in the male mammalian embryo, was evaluated for its antitumor effect on the premise that a substance active against this genital precursor in the fetus might also be active against tumors derived from these tissues. Increasingly pure fractions of biologically active MIS, prepared from newborn calf testes, were tested in the soft agar colony inhibition assay against single cell suspensions of fresh tumors derived in ascitic or solid form from patients with gynecologic malignancies. Twenty-eight tumor specimens placed in soft agar culture have provided sufficient growth to assess an MIS effect. Twenty-five of these 28 tumors showed significant colony inhibition after incubation with MIS. Increased antitumor response correlated with increased purification of MIS when the same tumor was treated with preparations of different purity. Samples obtained from the same patient at different times, from both ascites and solid tumor sources, produced nearly identical responses to MIS. MIS preparations, previously shown to be active in microcytotoxicity and colony inhibition assays against established human ovarian and endometrial carcinoma lines demonstrate consistent antitumor activity against fresh human gynecologic cancers removed at surgery.

Six-drug chemotherapy (hexamethylmelamine, doxorubicin, cisplatin, cyclophosphamide, methotrexate, and 5-FU; CHAMP-5) for ovarian carcinoma: alternating sequences of combination regimens

Twenty-five patients with previously untreated adenocarcinoma of the ovary (International Federation of Gynecology and Obstetrics, stages II, III, and IV) were placed on a six-drug trial (CHAMP-5) for 18 months. This trial consisted of 28-day cycles of hexamethylmelamine, doxorubicin, and cisplatin alternating with hexamethylmelamine, cyclophosphamide, methotrexate, and 5-FU. After a minimum follow-up of 31 months, 14 (56%) of the 25 evaluable patients achieved complete or partial response and nine (36%) achieved complete pathologic response. Although CHAMP-5 is effective in the treatment of ovarian cancer, the results in these patients are not substantially different from those achieved with hexamethylmelamine, doxorubicin, and cisplatin alone.

Phase II trials of hexamethylmelamine, dianhydrogalactitol, razoxane, and beta-2'-deoxythioguanosine as single agents against advanced measurable tumors of the pancreas. Gastrointestinal Tumor Study Group

Phase II trials of several single agents demonstrated only minimal objective response rates in patients with pancreatic carcinoma and measurable tumors: hexamethylmelamine (7%; four responses among 55 patients); dianhydrogalactitol (2.5%; one response among 40 patients); razoxane (7%; two responses among 29 patients); and beta-2'-deoxythioguanosine (6%; two responses among 32 patients). Among patients with a good performance status (0-2) and no prior chemotherapy, response rates were 8% for hexamethylmelamine (two responses among 26 patients); 8% for dianhydrogalactitol (one response among 13 patients); 8% for razoxane (one response among 12 patients); and 10% for beta-2'-deoxythioguanosine (two responses among 20 patients). None of these agents given by the methods of this study offers substantive benefit to the patient with advanced pancreatic cancer.

Short term high density systemic therapy for metastatic breast cancer

Twenty-three patients with metastatic breast carcinoma were induced with a complex systemic therapy regimen in an attempt to ascertain if a complete remission rate greater than 50% could be obtained with intensive drug exposure. The durability of the remissions was observed by discontinuing therapy after 3 cycles in complete remission or after 6 cycles of treatment, whichever was longer. In 13 patients consolidation radiation therapy to the pre-treatment sites of disease was administered after discontinuing systemic therapy. Each 28 day cycle of the drug regimen consisted of pulses of adriamycin, vincristine, dibromodulcitol, prednisone, methotrexate with leukovorin rescue, hexamethylmelamine, bleomycin (discontinued after entry #17), fluoxymesterone, and tamoxifen. Eighteen of the 23 patients achieved complete remissions (78%) and 3 had partial remissions. The median times to treatment failure and survival were, respectively, 12.3 and 19.4 mos. The times for complete remission patients were, respectively, 13.5 and 23.9 mos. Consolidation radiotherapy at greater than or equal to 40 Gy to drug induced pre-study sites of complete remission was associated with first relapses at pre-study sites in 5/30 (17%) instances, compared to 21/35 (60%) in sites not receiving radiotherapy. Side-effects were commensurate with the intensity of the treatment program and are detailed in the text. Although the achievement of a high complete remission rate is promising, the failure to extend their duration beyond that of historical data suggests that additional conceptual and therapeutic approaches need to be explored.

Hexamethylmelamine, adriamycin, and cyclophosphamide (HAC) versus cis-dichlorodiamineplatinum, adriamycin, and cyclophosphamide (PAC) in advanced ovarian cancer: a randomized clinical trial

After stratification according to diameter of the largest residual tumor, 120 previously untreated ovarian cancer patients were randomized to receive adriamycin and cyclophosphamide in combination with hexamethylmelamine (HAC) or cis-dichlorodiamineplatinum (PAC). The surgical response rates were 66% to HAC and 70% to PAC, with median times to progression of 14 and 22 months and median survival times of 23 and 24 months, respectively. In patients with residual tumor greater than 2 cm the surgical response rates to HAC and PAC were 56% and 63%, with complete response rates of 13% and 21%, respectively. In two of five complete responders to HAC there has still been no progression at 38 and 48 months, with a median response duration of 25 months. Only one of the nine complete responders to PAC has relapsed, at 33 months, while in the eight others response is maintained at follow-up times of 35-64 months. Myelosuppression was generally mild and similar in the two arms. No significant nonhematological toxicity was reported. It is concluded that at a median follow-up time of 36 months HAC is as effective as PAC in terms of response, duration of remission, and survival in previously untreated advanced ovarian cancer.

[Research project of cancer chemotherapy]

Information exchange with regard to new antitumor agents has taken place through meetings dealing with various treatment areas within the US-Japan Cancer Research Program, contact between the National Cancer Institute (NCI) in the USA and the Cancer Chemotherapy Center, and meetings of the Early Clinical Trial Group of the EORTC. Cisplatin. VP16-213, 6-Thioguanine, DTIC and AMSA which were judged to be worth introducing to Japan from information obtained from the above sources were supplied by the NCI and clinical trials have been conducted. A joint study of advanced gastric cancer was conducted between the Northern California Oncology Group and a Japanese Cooperative Group involving 13 major institutions through the US-Japan Program. The study was meaningful for understanding the natural history of patients with gastric cancer in both countries.

Cisplatin-MECY (methotrexate-leucovorin rescue plus cyclophosphamide) versus cisplatin-CHAD (cyclophosphamide, hexamethylmelamine, doxorubicin, and cisplatin) as initial chemotherapy in stage III-IV ovarian adenocarcinoma

Thirty-three patients with advanced-stage ovarian adenocarcinomas, with no prior chemotherapy, were treated with weekly cisplatin (DDP) for four courses followed by five monthly courses of one of two randomly assigned multidrug combinations. These combinations were high-dose methotrexate-leucovorin plus cyclophosphamide (MECY) or cyclophosphamide, hexamethylmelamine, doxorubicin, and DDP (CHAD). Patients with no clinically measurable disease after 6 months of therapy were evaluated by laparoscopy. In the absence of disease progression at the time of the laparoscopy the study design called for a repeat cycle of four weekly DDP courses and another five monthly courses of the assigned multidrug combination. All patients with no evidence of disease after 1 year of treatment had a second-look laparoscopy which, if negative, was followed by a second-look laparotomy. This report includes all of the consecutively entered patients observed for a minimum of 1 year or to death. DDP-MECY and DDP-CHAD were similarly active for overall response rates and complete response rates according to laparoscopic criteria. However, DDP-MECY had a statistically significantly lower relapse rate (P less than 0.02) and a statistically significantly higher negative second-look laparotomy rate than did DDP-CHAD. Using all entered patients, with no exclusions from analysis, eight of 17 patients (47%) treated with DDP-MECY had negative second-looks after 1 year of treatment. This compares with one of 16 (6%) negative second-looks in patients treated with DDP-CHAD (P less than 0.02). The high negative second-look rate with DDP-MECY is exciting. Positive cytologic washings at the 6-month laparoscopic evaluation were highly predictive that residual disease would be found at the 1-year second-look surgery. Only one patient with positive peritoneal cytology after 6 months of treatment was found to have a negative second-look after 1 year of therapy.

Nonhormonal chemotherapy in endometrial cancer--a review

A review of single agents and combination chemotherapy, with or without progestins, in the treatment of recurrent or metastatic endometrial carcinoma is presented. Doxorubicin, hexamethylmelamine, and cis-diamminedichloroplatinum are considered to be the most active drugs for the treatment of this disease. To date, combination chemotherapy has not shown any advantage over single agent therapy. The role of progestins in the treatment depends upon the presence of progesterone receptor binding sites. Better designed, randomized multi-institutional trials, using these drug combinations or new agents, singly or in combination, are necessary to identify optimal chemotherapy for patients with advanced or recurrent endometrial cancer.

Current status of systemic chemotherapy in the treatment of advanced ovarian cancer with emphasis on CHAP-5

In patients with advanced ovarian cancer, initial treatment with combination chemotherapy, including cyclophosphamide and cis-platinum diamminedichloride (cis-platinum), produces response and progression-free survival results which are superior to those achieved with alkylating single-agent chemotherapy. Unfortunately most schedules have not resulted in a statistically significant improvement of overall survival. So far one of the most effective combination regimens is the four-drug regimen CHAP-5 that consists of cyclophosphamide, hexamethylmelamine, adriamycin, and cis-platinum. This regimen is the first schedule to result in significant improved survival times compared with a second combination schedule, i.e. Hexa-CAF, which is at least as good as alkylating therapy alone. The CHAP-5 regimen was rather toxic but it was manageable and easy to apply in daily practice. Further improvement of the treatment results in advanced ovarian carcinoma will be difficult because no effective new drugs are available. In future clinical research it must be tried to decrease the toxicity and morbidity of the current schedules without reducing efficacy and survival.

Hexamethylmelamine in advanced head and neck cancer. A phase II study

The results of hexamethylmelamine therapy in 20 patients with advanced squamous cell head and neck cancer are reported. No patient had previously received chemotherapy. The dose of hexamethylmelamine was 8 mg/kg/day p.o. There was partial response in 3/20 (15%) patients. The duration of the response was 6-10 weeks. Twelve of 20 (12/20) patients had stable disease for a median of 8 weeks (range: 4-18 weeks). Hexamethylmelamine was well tolerated with the only significant toxicity being mild nausea and vomiting. This drug deserves further evaluation in the treatment of head and neck cancer.

The chemosensitivity of a new experimental model--the M5076 reticulum cell sarcoma

The M5076 reticulum cell sarcoma is a murine tumour of potential value in experimental chemotherapy. Experiments were conducted to ascertain the growth characteristics and chemosensitivity of this neoplasm in the BDF1 mouse. The intramuscular tumour proved to be responsive to the alkylating agents, nitrosoureas, procarbazine, DTIC and treosulphan, yet insensitive to the antimetabolites and only weakly responsive to adriamycin. Analogues of the antitumour agents hexamethylmelamine and N-methylformamide were tested against this neoplasm. The patterns of activity determined for these analogues against this tumour were identical to those previously reported against other model systems.

Predictive testing with the subrenal capsule assay

Measurement of drug activity as an oncolytic effect, use of the control only to monitor the quality of tissue implanted, and the rapid clearance of necrotic tissue from the subcapsular site, as significant factors incorporated into the design of the assay, have permitted use of a simple tumor size parameter for evaluating drug activity. The simplicity and economy of such a parameter, the predictability and reproducibility of the 6-day assay observed thus far, and evidence that the assay does measure a biological property of the tumor apart from host response, have warranted the continued use of the 6-day time frame and the normal immunocompetent CDF1 mouse as xenograft host. These studies have demonstrated the feasibility of using human tumor explants obtained from a variety of solid human malignancies in a straightforward, short term, in vivo predictive assay system. Preliminary correlations between in vivo (assay) tumor sensitivity and clinical response have given reasonable concurrence. This crucial point will require further study, with larger numbers of patients, under more rigid conditions. Final validation of this, and other, predictive assays will require a prospective, randomized study in large numbers of patients. Our present prospective study is being continued, therefore, with expansion to a multi-institutional design over a broader geographic area.

Failure of hexamethylmelamine as salvage therapy in ovarian epithelial adenocarcinoma resistant to combination chemotherapy

Favorable responses to hexamethylmelamine (HMM) have been documented in untreated as well as in alkylating agent-resistant ovarian epithelial adenocarcinoma (OvCa). Platinum-based combination therapy for OvCa has been used since 1976. Eighteen patients with OvCa were treated with HMM as salvage therapy between February 1979 and October 1981. All patients had histologically confirmed OvCa. Eleven tumors were grade III/III and seven tumors were grade II/III. Sixteen patients had received cisplatin-based combination therapy, whereas two had received doxorubicin/cyclophosphamide because of other medical conditions. HMM was used alone in 16 patients and in combination with other drugs in two patients. The initial dose of HMM was 300 mg/m2/day X 14 days when used alone and 130 mg/m2/day X 14 days when used in combination with other drugs. Six patients were treated at a reduced initial dose because of prior marrow toxicity. Adverse effects were tolerable, with 14 patients experiencing hematologic toxicity (5 mild, 5 moderate, 3 severe, 1 life threatening) and 15 patients experiencing GI toxicity (5 mild, 7 moderate, 3 severe). Only 2 patients experienced no toxicity. No objective tumor responses were observed. Four patients had progression of tumor within 4 weeks of starting therapy and 14 patients had stable disease with a mean progression-free interval of 21 weeks. Although HMM is an active drug in untreated and alkylating agent-resistant OvCa, experience suggests that HMM at the dose and schedule tested has insignificant activity in patients who have failed cisplatin-based combination therapy.

The chemotherapy of granulosa cell tumors of the ovary: experience of the Wisconsin Clinical Cancer Center

We reviewed the clinical records of 32 patients with granulosa cell tumor of the ovary treated at the Wisconsin Clinical Cancer Center (WCCC) between 1970 and 1982. Eleven of these patients were treated with one or more chemotherapeutic regimens, yielding a total of 22 treatment trials. Objective response was observed in 7 of 17 evaluable treatment trials (41%). The response to chemotherapy could not be assessed in five treatment trials due to the concomitant administration of radiotherapy. We conclude that granulosa cell tumor of the ovary is responsive to chemotherapy. However, the optimal chemotherapeutic regimen for this rare neoplasm remains to be established on the basis of prospective clinical trials.

The curative action of hexamethylmelamine on intramuscularly or intracerebrally implanted Yoshida sarcoma

Curative effects of hexamethylmelamine (HMM, NSC 13875) against intramuscularly or intracerebrally implanted Yoshida sarcoma depend on the schedules. A twice daily oral administration over a 2-week period showed a significant chemotherapeutic advantage over a single daily administration. The observed curative effect depends on the tumour site and on its mass. The Yoshida sarcoma seems to be one of the most suitable test models for HMM or related derivatives.